An important property which must be present in elastomeric compositions employed in a variety of uses, such as in tires for off-road and heavy service vehicles, belts, hoses, dust boots, diaphragms and other flexible mechanical devices, is desirable resistance to cut growth. Cut growth resistance under dynamic conditions, which is determined by means of the De Mattia flex test (ASTM D-430), is essential for such devices to provide a desirable long service life.
Moreover, it would be highly desirable to have available rubber blends which combine the toughness and other desirable properties of highly unsaturated rubbers (such as oil resistance in the case of butadiene/acrylonitrile rubber) with the ozone resistance of saturated rubbers (such as ethylene-propylene elastomers), which blend would additionally exhibit desirable cut growth resistance.
In the past, producrng a cured blend of highly unsaturated and saturated rubbers has been difficult, with the resulting product typically exhibiting physical properties inferior to those of such rubbers alone. This phenomenon is commonly ascribed to the co-cure incompatibility of unsaturated and saturated rubbers due to their polarity and differing degrees of saturation. In addition, migration of curatives between the saturated and unsaturated components can also lead to curing difficulties. Moreover, there has been no indication of unexpectedly enhanced cut growth in such compositions.
Consequently, it would be desirable to have a rubber composition which exhibited the toughness of highly unsaturated rubber and the ozone resistance of saturated rubber, which rubber composition additionally provided enhanced resistance to cut growth Accordingly, it is an object of this invention to provide a rubber composition which exhibits desirable strength and resistance to oxidation, which composition also possesses desirable resistance to cut growth.
It is a further object of this invention to provide a process for the production of such a rubber composition.
The above and additional objects will become more fully apparent from the following description and Examples.